The answer is "2", and this is an absolutely terrible series of problems that barely explains why anyone should care. Even knowing what I know about Church numerals I feel that all these questions are doing is irritating the user.

the last question Evaluating Expressions #3, was changed to the more reasonable "what Church numeral does this expression correspond to", but this question still has the nonsensical "compute the integer value". The change should be made here as well.

The way I think of church numerals is as follows.
0 is defined as just your input so x
1 is defined as applying a generic function once to your generic input so f(x)
2 is f(f(x))
and so on. In lambda calculus this 2 would be expressed as
λf.λx.f f x.